I'm in the same boat as you; just bought Sealed Power pistons (+.060), and a Hastings moly ring set.There's more to this than meets the eye. I will put the wrist pins and keepers in the old set, weigh them, and find the DIFFERENCE in weight from the new set. To keep crankshaft counterweights consistant, I need the new pistons to weigh the same as the old set. Because my old rings were really far gone, bare pistons with pins and keepers will be used, leaving out all the rings.
Of course, you want your new pistons to weigh the same, so do that first (they should be real close out of the box). But the DIFFERENCE can be taken off that square on top of your connecting rods. Here's the balancing act: Weigh the rod ends, make them the same, then continue grinding off the small end tops off, to compensate for the additional new bigger piston weight. Removing steel gives much faster results than removing aluminum alloy. When done, re-check your weights. Your crankshaft will thank you.
One reason new engines last so much longer is because they come from the factory with moly top-rings and cast iron second-rings. I'm going to start a fight here, but another reason they last longer is because they run hotter. Cold engines wear much faster than hot. Iron heads can't dissipate heat much over 180*, but aluminum heads have no problem with 195* or more (notice we're approaching the boiling point). New engines also use 16-lb radiator caps, which raise the boiling point to over 250*F (just like a pressure cooker). The formula is, for every pound of pressure, the boiling point raises about 3*. Note: Distilled water boils at 212*F at sea level. Glycol & water slightly helps the boiling point but really lowers the freezing point. Some antique cars use NO radiator pressure. When they climb the Rocky Mountains at 12,000 ft, they are screwed. Up there, an egg takes over 1/2 hour to hard-boil because atmospheric pressure is so low.